Breast pumps are well known devices for extracting milk from a breast of a user, for example as known from US 2005/234370. A breast pump may be used if the baby is not itself able to extract the milk, or if the mother is separated from the baby, for example if away from the baby at work. The use of a breast pump to extract milk may also be used to stimulate lactation in women with a low milk supply, or to relieve engorgement.
Breast pumps may be manually operated, for example by squeezing a handle or operation of a foot pedal. Breast pumps may also be electrically driven by a small electric motor.
The expression of milk using a breast pump may be difficult for a user. In order to effectively express milk, it is important that the user is relaxed. The hormone oxytocin plays a vital role in milk expression, and stress inhibits its release. For milk expression to occur, oxytocin is released in the blood stream, and is transported to the breast. This causes the myoepithelial cells that cover the milk glands to contract. Contraction of the cells around the milk glands and shortening of the milk ducts pushes the milk out of the glands towards the nipple where it is expressed into the breast pump.
If release of oxytocin is inhibited, the cell contraction that pushes the milk out of the glands may be disabled. When milk is not removed from the breast, an inhibitory factor signals to the body to cease production of milk, and so the milk supply can rapidly diminish.